This invention provides a method of simplifying and improving conventional beam breaker radar systems used for intruder detection devices around high value isolated resources like parked aircraft. In present systems, four separate radars are located at the corners of a square which defines the zone to be protected. Any intruder crossing a boundary of the zone interrups the radar beam and sounds an alarm.
The present invention uses only one active bistatic radar, three or four passive reflectors to redirect the beam at the corners, and, if needed, some passive in-line focusing devices. This reduces the number of components required and provides other advantages such as reduced economic costs.
One of the novel features of this system is the use of passive reflectors at the corners of the protected zone to redirect the radar beam. Another feature is the use of phase cancelling and balancing techniques to increase system sensitivity. Yet another feature enables greater flexibility in system design since transmitter and receiver are co-located and power need may be supplied to only one point on the perimeter.
It is further noted that the radar intrusion system improves performance in a number of ways such as: (a) requires fewer active components so that it is cheaper and more reliable; (b) no loss of sensitivity at corners; (c) reflectors are efficient passive devices; (d) shape of protected area can be changed by moving only passive devices, and (e) enables greater flexibility in system design since power requirements are greatly reduced.